The common practice of hyperextending the neck with a shoulder roll in preparation for open tracheostomy slides more of the trachea up out of the superior thoracic aperture, facilitating access. However, the temptation to avoid dividing the thyroid isthmus crossing the second tracheal ring may lead to placing the opening in a lower ring. Attempted puncture below the isthmus is also a goal of the percutaneous nethod. When the neck is returned to its anatomic position, the hub of the tracheostomy tube comes to rest on the top of the manubrium and the tip of the tube is levered anteriorly where it can erode through trachea into brachiocephalic artery. Emergency compression by a finger between trachea and artery, compressing the artery against manubrium until the patient can reach the operating room, is seldom successful in saving the patient.
The superior arteries descend on the apices of the lobes, while the inferior arteries approach the posterior surfaces of the lower portions of the lobes. The isthmus of the gland overlies the second tracheal ring. The junction of isthmus and lobe is densely attached to the trachea (suspensory ligament of Berry) and needs to be separated by sharp dissection during lobectomy or thyroidectomy. The isthmus, however, can be separated from the underlying tracheal ring, divided and ligated in the course of tracheostomy with little difficulty.